At present the condition of the electrical system in vehicles with combustion engine is indicated by an electromechanical or digital voltmeter. In addition an extra conductor may be run from the generator to an indicating light on the instrument panel. The common vehicular driver cannot make judgment with the indication provided by the voltmeter and therefore is useless for him, it is only an ornament for him.
U.S. Pat. No. 4,027,231 indicates only discharging condition of storage batteries.
U.S. Pat. Nos. 4,943,777; 5,130,659 and 5,496,658 teach devices extremely complex.